In the 29 April 2009 by-election, the NPP looked to win a seat for the district of Ulsan based on its pro-Labor population statistics.

The NPP negotiated with the Democratic Labor Party to nominate the Progressive sole candidate before the beginning of the by-election.

In the by-election, Cho beat the GNP (Grand National Party) candidate and the NPP finally took one seat.

In the 2010 local government election of mayor of Seoul, NNP candidate Roh Hoe-chan received 3% of the vote.

In December 2011, a faction of the NPP, led by Sim Sang-jeong, left to join the Unified Progressive Party.

In particular, the NPP showed a more hostile tendency than South Korean liberals when it comes to North Korea policy.